New York Mets left-hander Johan Santana likely will need a second—and possibly career-ending—surgery on his pitching shoulder.

Mets general manager Sandy Alderson told reporters on a conference call Thursday evening that an MRI exam Wednesday revealed a probable tear in the same area of Santana's shoulder that was repaired in September 2010. He said that surgery is "a strong possibility."

Johan Santana, right, with Mets manager Terry Collins, could miss the 2013 season with a second shoulder tear. (AP Photo)

"We don't know when it happened, how it happened," Alderson said. "But what we do know is that at some point symptoms appeared and they worsened rather than improved."

Santana is expected to decide in the next few days whether to have another operation.

Santana, 34, was already scheduled to begin the season on the disabled list. He has missed the entire exhibition season because of a lack of arm strength.

Santana didn't pitch in the major leagues in 2011 following shoulder surgery. He went 6-9 with a 4.85 ERA in 21 starts last season and pitched the first no-hitter in Mets history June 1.

His season ended in mid-August because of lower back inflammation, and he did only light tossing during the offseason, leaving him behind schedule when he reported to camp last month.

Santana acknowledged last week that "not everything was there as far as my strength in my shoulder."

"Coming into this spring training I felt great. I was very excited and everything changed in a couple days," he said.

Santana gets $25.5 million this year in the final guaranteed season of his $137.5 million, six-year contract. The Mets hold a $25 million option for 2014 with a $5.5 million buyout. None of the $31 million (salary plus buyout) is insured.

Alderson claimed Santana's injury will not lead the Mets to rush 22-year-old right-hander Zack Wheeler, their top pitching prospect, to the majors.

"We will bring him up when he is ready," Alderson said. "No immediate need will impact that."